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The strategy of fly-and-forage migration, illustrated for the osprey (Pandion haliaetus)

Publiceringsår: 2007
Språk: Engelska
Sidor: 1865-1875
Publikation/Tidskrift/Serie: Behavioural Ecology and Sociobiology
Volym: 61
Nummer: 12
Dokumenttyp: Artikel
Förlag: Springer Berlin / Heidelberg

Sammanfattning

Migrating birds often alternate between flight
steps, when distance is covered and energy consumed, and
stopover periods, when energy reserves are restored. An
alternative strategy is fly-and-forage migration, useful mainly
for birds that hunt or locate their prey in flight, and thus,
enables birds to combine foraging with covering migration
distance. The favourability of this strategy in comparison with
the traditional stopover strategy depends on costs of reduced
effective travel speed and benefits of offsetting energy
consumption during migration flights. Evaluating these costbenefit
effects, we predict that fly-and-forage migration is
favourable under many conditions (increasing total migration
speed), both as a pure strategy and in combination with
stopover behaviour. We used the osprey (Pandion haliaetus)
as test case for investigating the importance of this strategy
during spring and autumn migration at a lake in southern
Sweden. The majority, 78%, of passing ospreys behaved
according to the fly-and-forage migration strategy by
deviating from their migratory track to visit or forage at the
lake, while 12% migrated past the lake without response,
and 10% made stopovers at the lake. Foraging success of
passing ospreys was almost as good as for birds on stopover.
Timing of foraging demonstrated that the birds adopted a
genuine fly-and-forage strategy rather than intensified
foraging before and after the daily travelling period. We
predict that fly-and-forage migration is widely used and
important among many species besides the osprey, and the
exploration of its occurrence and consequences will be a
challenging task in the field of optimal migration.

Disputation

Nyckelord

  • Biology and Life Sciences
  • Bird migration . Migration strategies . Foraging . Stopover . Osprey

Övriga

Published
Yes
  • ISSN: 0340-5443
  • ISSN: 1432-0762

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